1. Field of the Invention
This invention relates to a scroll compressor used in refrigeration air conditioning for business use and domestic use.
2. Related Art
Electrically-operated compressors, used in refrigeration air conditioning, are classified into those with a reciprocating compressing portion and those with a rotary compressing portion, and both have been used in the field of refrigeration air conditioning for business use and domestic use, and have grown up, taking advantage of their cost and features. Scroll-type compressors have been put into practical use, taking advantage of high-efficiency, low-noise and low-vibration features.
U.S. Pat. No. 3,874,827 discloses a construction in which a back pressure, produced by a discharge fluid, is exerted on a non-orbital, stationary scroll which is movable in an axial direction, and the stationary scroll is urged or pressed toward a movable scroll by this back pressure.
In such a construction, the sealing of several compression chambers, formed between the stationary and movable scrolls, can be enhanced, and the performance can be enhanced with a simple construction.
Generally, there has been used a construction in which wraps of stationary and movable scrolls are pressed against each other in a radial direction with a suitable force so as to reduce a leakage in the radial direction of the wraps. However, when the stationary scroll is so designed as to move in the axial direction, a force, tending to overturn the stationary scroll, is produced by the force, pressing the wrap of the movable scroll against the wrap of the stationary scroll, and a force of the compressed gas, so that the stationary scroll precesses. This precession occurs once per revolution, and therefore a vibration is applied to an annular seal member. One of inner and outer sides of the annular seal member contacts the precessing stationary scroll while the other side contacts an immovable stationary scroll support member, and the annular seal member separates a suction pressure portion, which applies a back pressure to the stationary scroll, from a discharge pressure portion. When a vibration is thus applied to the annular seal member, the annular seal member is liable to produce wear powder, and this wear powder is drawn into a compression mechanism portion, comprising the stationary scroll and the movable scroll, and is compressed, and flows into a refrigerating cycle connected to the compressor, and it is possible that this causes the clogging of filters in an expansion valve and other associated portions. In view of sealing properties, the annular seal member is, in many cases, made of a resin, and the amount of wear of the annular seal member will not adversely affect the reliability of the compressor. However, there is a high possibility that the wear powder is produced in an amount above an allowable dirt amount for the refrigerating cycle.